Balanced combustion with multi-cylinder, poppet valve internal combustion engines is important for reliable, emission-compliant operation. The typical reciprocating engine is designed to proportionately distribute the compressor and auxiliary loads between the engine's power cylinders. Unfortunately, a number of factors introduce variability into the cylinder-to-cylinder combustion process. One such factor is intake manifold design.
Several benefits are realized when an engine's combustion is balanced. First, combustion temperatures can be controlled, which stabilizes exhaust emissions. Second, fuel consumption can be minimized. Third, excessive stress on engine components, created by high cylinder pressures, is minimized, maximizing engine reliability. Fourth, engine balancing controls peak combustion pressures within the cylinders. Finally, the horsepower load is distributed proportionately across the cylinders.
Historically, a number of methods have been employed to help reduce cylinder-to-cylinder variability. However, most of these methods involve making inaccurate adjustments to the fuel/air delivery system in an attempt to direct higher flow toward “starving” cylinders and lessen the flow directed to “over-powered” cylinders. One method rotates the position of the carburetor with respect to the manifold. Another method involves changing the size of the jets inside the carburetor. Other methods swap manifolds, experimenting with various wave harmonics. Still another method involves the installation of air flow balancing valves in the manifold, upstream of the cylinders' fuel injection valves.
A certain amount of carbon buildup is normal in all engines.
Most late-model engines with computer controls have one or more knock sensors to detect detonation. If a knock sensor picks up vibrations within a certain frequency range, it signals the computer to back off ignition timing a certain number of degrees until the vibrations go away. Knock retard works up to a point, but the trade off is reduced performance and fuel economy as long as the timing is retarded.
The “valve train” within poppet valve internal combustion engines, typically includes the camshaft, valve lifters, valves, valve springs, retainers, rocker arms and shafts. On engines with the camshaft in the cylinder block, the valve train also includes pushrods. Overhead cam engines may use more than one camshaft per cylinder head. Engines use different valve configurations, such as two, three, or four valves per cylinder. These various valve arrangements are used for different engine breathing requirements. Changes to the valve train, such as exchanging camshafts, increasing the ratios of each of the rocker arms, and upgrading valve train components to reduce friction, and reduce weight have been implemented to change an engine's horsepower, fuel consumption rate, emissions levels and the like. Uniform changes along the valve train, using readily available, off-the-shelf parts, can be relatively quick and inexpensive to implement by professional mechanics and shade-tree mechanics alike. However, such changes fail to adequately address cylinder to cylinder variability.
Accordingly, what is needed is a novel method of engine calibration to reduce cylinder to cylinder variability that can be used in mass production settings and that is relatively quick and inexpensive to implement in retrofit situations by mechanics of varying abilities. However, such a method should effectively contribute to engine balance.